CN111635867B

CN111635867B - Oil-producing yeast and application thereof

Info

Publication number: CN111635867B
Application number: CN202010546363.0A
Authority: CN
Inventors: 孙付保; 周秋利; 胡芸; 任洪艳; 龙凌凤
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2020-06-15
Filing date: 2020-06-15
Publication date: 2022-03-15
Anticipated expiration: 2040-06-15
Also published as: WO2021254076A1; CN111635867A; US20220170058A1

Abstract

The invention discloses an oleaginous yeast and application thereof, belonging to the technical field of microorganisms. The Dermatopteris chrysosporium (Trichosporon dematis) provided by the invention is preserved in China center for type culture Collection in 5-21 months in 2020, and the preservation number is CCTCC NO: m2020139. The oil-producing yeast provided by the invention can use the hydrolysate of the cheap lignocellulose biomass as the substrate, and can produce oil by using xylose and glucose in the hydrolysate, so that the sugar utilization efficiency and the production intensity are improved, and after the fed-batch fermentation is carried out for 8 days, the oil yield can reach 31.33g/L, and the oil content is 60.83%. The waste resources can be reused, the production cost is reduced, and the method has wide application prospect.

Description

Oil-producing yeast and application thereof

Technical Field

The invention relates to an oleaginous yeast and application thereof, belonging to the technical field of microorganisms.

Background

Some microorganisms such as yeast, bacteria, mold and microalgae can accumulate oil using carbohydrates, hydrocarbons and oils as carbon sources, and any microorganism in which the amount of accumulated oil exceeds 20% of the dry weight of cells is called an oleaginous microorganism. The fatty acid composition of the microbial oil, especially the oil produced by yeast, is similar to that of vegetable oil, and the microbial oil mainly contains C16 and C18 series fatty acids, such as palmitic acid, stearic acid, oleic acid and the like. The microbial oil can replace expensive animal and vegetable oil as a raw material for producing the biodiesel, and has a positive effect on promoting the large-scale industrial production of the biodiesel. In addition, the oil-producing microorganism also has the advantages of short fermentation period, no influence of seasonal climate, wide carbon source utilization and the like, has good development prospect, and plays an important role in the development of the biodiesel industry in the future. However, the development of microbial oils is limited by the problems of high cost of carbon source for culturing microbes and low yield of microbial oils.

China is a big agricultural country, 7 hundred million tons of straw biomass are produced in a big date every year, and with the addition of forestry processing residues, the agricultural and forestry fiber biomass residues produced in China every year are up to 20 hundred million tons, but China does not effectively utilize the biomass. The biomass contains rich carbohydrates (cellulose and hemicellulose), and can obtain glucose after being fully hydrolyzed, so that the requirement of growth and metabolism of the oleaginous yeast on a carbon source can be met. The hydrolysate containing the cellulosic sugar is used for culturing the oil-producing yeast, so that the production cost of the microbial oil can be greatly reduced, and the possibility of realizing the scale production of the microbial oil is provided.

In addition, the agriculture and forestry biomass hydrolysate not only contains abundant glucose, but also can obtain monosaccharides such as xylose and the like. However, most microorganisms have a glucose effect during their metabolism, i.e., glucose is preferentially utilized when the medium contains glucose and xylose, and xylose utilization is initiated only when the glucose concentration is low. The mechanism can cause the technical problems of long fermentation period by using the hydrolysate, low utilization rate of cellulose resources, high production cost and the like. Therefore, obtaining high-yield grease yeast capable of simultaneously utilizing glucose and xylose mixed sugar is an important direction in the technical field of microbial grease.

Disclosure of Invention

The invention aims to provide a method for producing microbial oil by fermenting yeast with high-yield oil through cellulosic hydrolysate. In order to overcome the defect that the oil yield of the grease yeast is not high, the wild grease yeast ZZ-46 is used as an initiating bacterium, cerulenin and TTC with certain concentration are used as screening factors to primarily screen mutants, and Nile red fluorescence detection is used for high-throughput screening of primarily screened mutant strains to finally obtain the high-yield grease yeast with stable genetic character. And the cellulose hydrolysate can be directly utilized to ferment and produce the oil, so that the oil-producing microorganism culture can more efficiently utilize the raw materials from the lignocellulose, the technical economy of the microbial oil production is improved, and the method has wide application prospect.

The oleaginous yeast (Trichosporon dematis) provided by the invention is preserved in China center for type culture Collection in 5-21 months in 2020, and the preservation number is CCTCC NO: m2020139.

The invention provides a method for simultaneously utilizing xylose and glucose, and the oil-producing yeast is added into a system containing xylose and glucose.

In one embodiment of the invention, the oleaginous yeast is fermented at 22-28 ℃ for 7-9 days.

In one embodiment of the invention, the oleaginous yeast is added to a fermentation system for fermenting oleaginous.

In one embodiment of the present invention, the carbon source in the fermentation system is derived from a hydrolyzed mixed sugar solution of a lignocellulosic biomass feedstock.

In one embodiment of the present invention, the method for preparing the hydrolyzed mixed sugar solution comprises:

(1) pretreating a lignocellulose biomass raw material by using an alkali-catalyzed normal-pressure glycerol organic solvent: weighing 90-150 g of dry lignocellulose biomass raw material, putting into a 1000-5000 mL three-neck flask, and then adding 900-1500 g of glycerol and 0.2% (w/w) of NaOH solid; putting the three-neck flask filled with the matrix into a constant-temperature heating jacket, and simultaneously mechanically stirring to uniformly mix the matrix and keeping the temperature of 200-250 ℃ for 8-12 min; after the reaction is finished, 1000-1500 mL of tap water is poured into the flask to fully dissociate the substrate, then the substrate is filtered by a G1 sand core funnel, the filter cake is washed twice by 1500-2000 mL of tap water and is filtered, and finally the obtained filter cake is the lignocellulose biomass substrate. Dividing the matrix into two parts, airing one part until the water content is 45-55%, and storing at 2-4 ℃; the other part is dried in an oven at 100-110 ℃ until the weight is dead;

(2) enzymolysis of the pretreated matrix: weighing 10-20 g of substrate with water content of 45-55%, putting the substrate into a 150-250 mL round-bottom flask, and adding 2-5 FPU g^-10.5-1.0 mL of dry cellulase (the raw enzyme solution is diluted to 55-65 FPU g by using a citric acid buffer solution)^-1) And additives PEG 4000180-200 mg, triton X-100350-400 mg, tea saponin 180-200 mg, bovine serum albumin 180-200 mg and xylanase 20-25 mg, and adding 45-55 mL of citric acid buffer solution (50mM, pH 4.5-5.0); respectively supplementing 3.0 hours in 10-12 hours, 22-24 hours and 34-36 hours of enzymolysis3.5g, 2.5-3.0 g and 2.5-3.0 g of dry basis; carrying out enzymolysis for 68-78 h at 45-55 ℃; 8000-10000 r.min after enzymolysis^-1Centrifuging for 4-6 min.

In one embodiment of the invention, the lignocellulosic biomass comprises agricultural straw and forestry processing residue-like waste feedstock.

In one embodiment of the invention, the OD is₆₀₀6-8 percent of the oil-producing yeast is added into a fermentation system in an amount of 5-10 percent.

In one embodiment of the invention, the total sugar content in the fermentation system is 70-90 g/L; the nitrogen source is soybean peptone, NH₄Cl or yeast extract; carbon/nitrogen (273-373) to 1.

In one embodiment of the present invention, the liquid content of the fermentation liquid in the fermentation system is 12% to 20%.

In one embodiment of the invention, feeding is carried out in the fermentation process, wherein the feeding is carried out by feeding a mixture of glucose and xylose with the final concentration of 10-20 g/L, and the ratio of the glucose to the xylose in the mixture is (1-2) to 1.

In one embodiment of the invention, the oleaginous yeast is fermented at 22-28 ℃ and pH 6-8 for 7-9 days.

The invention also protects the application of the oil-producing yeast, or a method for simultaneously utilizing xylose and glucose, or a method for improving the oil yield in the oil production in the fields of food, medicine, agriculture and chemical industry.

The invention has the beneficial effects that:

the agricultural and forestry lignocellulose biomass waste is a renewable resource with high cellulose and hemicellulose content, has wide source and low cost, but because the hydrolysate contains mixed sugar of glucose and xylose, the mixed sugar culture microorganisms usually have glucose effect, so the fermentation period is long and the efficiency is low. The high-yield grease yeast obtained by the invention can simultaneously utilize glucose and xylose to accumulate a large amount of grease, the sugar utilization efficiency and the production intensity are improved, and after fed-batch fermentation is carried out for 8 days, the grease yield can reach 31.33g/L, and the grease content is 60.83%. The waste resources can be reused, the production cost is reduced, and the method has wide application prospect.

Biological material preservation

The Dermatopteridium sp provided by the invention is classified and named as Dermatopteridium sp L7 Trichosporon dematis L7, is preserved in China center for type culture Collection in 5-month and 21-month 2020, and has a preservation number of CCTCC NO: m2020139, the preservation address is China, Wuhan university.

Drawings

FIG. 1 shows the synchronous sugar consumption curve of the starter strain ZZ-46.

FIG. 2 is a graph of the simultaneous sugar consumption of strain L7.

FIG. 3 shows the results of fed-batch fermentation of strain L7 in a 5L fermenter with a 2: 1 fed-carbon source glucose/xylose.

FIG. 4 shows the results of fed-batch fermentation of strain L7 in a 5L fermenter with a 1:1 ratio of glucose/xylose as the carbon source fed.

Detailed Description

YPD solid Medium: 10g/L of yeast extract, 20g/L of peptone, 20g/L of glucose and 15g/L of agar.

YPD seed culture Medium: 10g/L of yeast extract, 20g/L of peptone and 20g/L of glucose.

Re-screening the fermentation medium: carbon source: 46.67g/L glucose, 23.33g/L xylose; nitrogen source: yeast extract 0.75g/L, NH₄Cl 0.1 g/L; inorganic salts: MgCl₂·6H₂O 1g/L、Na₂SO₄0.1 g/L; phosphate buffer: KH (Perkin Elmer)₂PO₄ 11.8g/L、K₂HPO₄·3H₂O3.7 g/L; trace elements: CaCl₂·2H₂O 40mg/L、FeSO₄·7H₂O5.5 mg/L, citric acid monohydrate 5.2mg/L, ZnSO₄·7H₂O 1mg/L、MnSO4·H₂O 0.76mg/L、18mol H₂SO₄ 1.84×10^-3mg/L, sterilizing and reserving for later use.

The wild oleaginous yeast strain used in the examples was Trichosporon. dermatis ZZ-46, deposited at the Nanyang commercial Collection of Industrial microorganisms with Strain number NICC 30027.

Preparing bagasse hydrolysate:

(1) alkali-catalyzed atmospheric-pressure glycerol organic solvent pretreatment of bagasse

100g of dried bagasse was weighed into a 5000mL three-necked flask, and 1000g of glycerol and 0.2% (w/w) NaOH solids were added. The three-neck flask with the matrix is placed in a constant temperature heating jacket, and the matrix is mixed uniformly by mechanical stirring and kept at 240 ℃ for 10 min. After the reaction is finished, 1500mL of tap water is poured into the flask to fully dissociate the matrix, then the mixture is filtered by a G1 sand core funnel, then the filter cake is washed twice by 2000mL of tap water and is filtered by suction, and finally the filter cake is the bagasse matrix. Dividing the matrix into two parts, air-drying one part until the water content is 50%, and storing at 4 deg.C; the other part is baked in an oven at 105 ℃ until the weight is extremely heavy.

(2) Enzymatic hydrolysis of pretreated substrate

Weighing 16g of substrate with water content of 50%, placing in a 250mL round bottom flask, adding 3FPU g^-1Dry basis cellulase 0.875mL (Prozyme solution diluted to 60FPU g using citrate buffer)^-1) And additives PEG 4000192 mg, triton X-100356 mg, tea saponin 193mg, bovine serum albumin 190mg, and xylanase 21mg, and adding 50mL with citric acid buffer (50mM, pH 4.8). 3.5g, 3g and 3g of dry basis are respectively supplemented at 12h, 24h and 36h of enzymolysis. The enzymolysis is carried out by mechanical stirring at the rotating speed of 150r and the temperature of 50 ℃ for 72 h. Centrifuging for 5min at 10000 r.min-1 after enzymolysis is finished, and taking supernatant to measure the concentration of glucose and xylose.

(3) Dilution of bagasse hydrolysate

The content of bagasse hydrolysate mixed sugar (208g/L) obtained by the method is as follows: 140g/L glucose and 68g/L xylose. Diluting the hydrolysate with deionized water 3 times to 70g/L or 2.6 times to 80g/L according to fermentation requirements, and adjusting pH to 6 with NaOH.

Example 1: mutation and selection of strains

(1) Preparation of bacterial suspension: activating the preserved wild oil-producing yeast strain, selecting a single colony in a YPD seed culture medium, culturing at 25 ℃ at 140r/min for 36h, and taking 1mL of bacterial liquid 8Centrifuging at 000r for 5min, collecting thallus, washing with sterile normal saline for three times, mixing on vortex instrument to disperse thallus, and adjusting suspension concentration to OD ₆₀₀1, preparing bacterial suspension for later use;

(2) ARTP mutagenesis: taking 10ul of wild grease yeast ZZ-46 bacterial suspension from an ultraclean workbench, coating the suspension on a sterile metal slide, placing the metal slide in a groove of an ARTP mutagenic instrument operation chamber object stage, setting the power to be 100W by taking nitrogen as working gas, setting the processing distance to be 2mm, setting the gas flow to be 10L/min and processing time to be 140 s;

(3) plate pre-screening: diluting the treated bacterial suspension with sterile physiological saline 10^-2Diluting, and applying to a container containing 1.67X 10^-3% of (w/v) TTC and 4.107X 10^-6Putting the screening plate of the cerulenin in mol/L into a constant temperature incubator at 25 ℃ to be cultured for 2 days in a dark place;

(4) high-throughput screening: picking the large red single colony on the screening plate, culturing in 48-well plate (1mL culture medium/well), culturing in shaking table at 25 deg.C and 200r/min for 2 days, transferring 100uL bacterial liquid to 96-well plate, and detecting OD with microplate reader₆₀₀The absorbance at nm characterizes the cell concentration. And adding 5uL of nile red solution into each pore plate, uniformly mixing, shading and dyeing for 5min, and characterizing the oil yield by using fluorescence intensity. The detected emission wavelength is 485nm, and the absorption wavelength is 595 nm. The fluorescence intensity was: subtracting the background fluorescence intensity of the sample without adding Nile red from the measured fluorescence intensity of the sample;

(5) DES mutagenesis: activating high-yield mutant strain obtained by ARTP mutagenesis, culturing with seed liquid to obtain bacterial suspension, and collecting OD₆₀₀2mL of the bacterial suspension (1) was added with 2mL of pH 7.0 phosphate buffer, and then 0.2mL of 50% diethyl sulfate-ethanol solution was added, followed by shaking at 25 ℃ for 70 min. After the treatment, 1mL of 25% sodium thiosulfate was added to the reaction mixture to terminate the reaction;

(6) screening after DES mutagenesis: and (4) performing plate pre-screening and high-throughput screening on the bacterial suspension subjected to the DES treatment according to the steps (3) and (4).

(7) And (3) shaking a flask for re-screening: and (3) selecting a single colony of the high-yield strain obtained by primary screening, inoculating the single colony in a YPD seed culture medium, culturing for 36h at 25 ℃ at 140r/min, inoculating the single colony in 50mL of basic fermentation culture medium according to the inoculation amount of 10%, and fermenting for 7 days at 25 ℃ at 140 r/min. The fermentation broth was centrifuged to collect the biomass, the oil yield of the fermentation broth and the oil content of the biomass, and the results are shown in table 1.

According to the measured relevant indexes, the strain L7 with better comprehensive effect is screened out and sent to the China center for type culture Collection for preservation.

TABLE 1 Re-screening of Strain Productivity

The strain L7 was subcultured (the culture method was the same as the rescreening), and the biomass, the oil yield and the oil content from the first generation to the seventh generation were examined. As can be seen from Table 2, the biomass, oil yield and oil content of the mutant strain were stable. The result shows that the strain has good genetic stability.

TABLE 2 passage stability of Strain L7

Example 2: fermenting with bagasse hydrolysate

Bagasse hydrolysate fermentation medium components: the bagasse hydrolysate is diluted to 70g/L total sugar, the pH is adjusted to 6, and other nitrogen sources, inorganic salts and other substances are not added.

Fermentation of bagasse hydrolysate: inoculating single colony of strain L7 into YPD seed culture medium, culturing at 25 deg.C and 140r/min for 36 hr to OD₆₀₀At 7.6, 50/250mL (i.e., 50mL fermentation medium in a 250mL conical flask) of bagasse hydrolysate medium was inoculated at 10% inoculum size and fermented at 140r/min at 25 ℃ for 7 days.

Producing oil by fermenting strains: the strain L7 is fermented in a bagasse hydrolysate fermentation medium, the biomass, the grease yield and the grease content of the strain are respectively 18.87g/L, 9.26g/L and 49.07% compared with the biomass, the grease yield and the grease content of the original strain ZZ-46, the biomass, the grease yield and the grease content of the original strain ZZ-46 are respectively 15.21g/L, 6.76g/L and 44.46%, wherein the biomass and the grease yield are respectively improved by 24.06% and 36.98% compared with the original strain.

Example 3: fermentation medium using bagasse hydrolysate as carbon source

Fermentation medium components using bagasse hydrolysate as carbon source: diluting bagasse hydrolysate to 70g/L total sugar, adjusting pH to 6, adding nitrogen source: yeast extract 0.75g/L, NH₄Cl 0.1 g/L; inorganic salts: MgCl₂·6H₂O 1g/L、Na₂SO₄0.1 g/L; phosphate buffer: KH (Perkin Elmer)₂PO₄ 11.8g/L、K₂HPO₄·3H₂O3.7 g/L; trace elements: CaCl₂·2H₂O 40mg/L、FeSO₄·7H₂O5.5 mg/L, citric acid monohydrate 5.2mg/L, ZnSO₄·7H₂O 1mg/L、MnSO4·H₂O 0.76mg/L、18mol H₂SO₄ 1.84×10^-3mg/L。

Producing oil by fermenting strains: inoculating single colony of strain L7 into YPD seed culture medium, and culturing at 25 deg.C and 140r/min for 36 hr to OD₆₀₀At 7.6, the cells were inoculated into 50/250mL of bagasse hydrolysate medium at an inoculum size of 10%, fermented at 140r/min at 25 ℃ for 7 days.

After the strain L7 is fermented in a fermentation medium with bagasse hydrolysate as a carbon source, the biomass, the oil yield and the oil content respectively reach 22.12g/L, 11.18g/L and 50.54%.

Example 4: strain L7 is fermented to produce oil under the shake flask optimization condition

Fermentation medium components: bagasse hydrolysate was diluted to 80g/L total sugar and soy peptone was added as nitrogen source, maintaining C/N273: 1, in addition to inorganic salts: MgCl₂·6H₂O 1g/L、Na₂SO₄0.1 g/L; phosphate buffer: KH (Perkin Elmer)₂PO₄11.8g/L、K₂HPO₄·3H₂O3.7 g/L; trace elements: CaCl₂·2H₂O 40mg/L、FeSO₄·7H₂O5.5 mg/L, citric acid monohydrate 5.2mg/L, ZnSO₄·7H₂O 1mg/L、MnSO4·H₂O 0.76mg/L、18mol H₂SO₄ 1.84×10^-3mg/L。

Producing oil by fermenting strains: inoculating single colony of strain L7 into YPD seed culture medium, culturing at 22 deg.C and 140r/min for 36 hr to OD₆₀₀At 7.6, the mixture was inoculated into 40/250mL bagasse hydrolysate medium at an inoculum size of 10%, the pH was adjusted to 6, 140r/min, and the mixture was fermented at 22 ℃ for 8 days.

The biomass, the grease yield and the grease content of the fertilizer reach 26.73g/L, 14.00g/L and 52.37%.

Example 5: fed-batch fermentation under shake flask conditions

See example 4, on the basis of which four feeding modes are designed: the initial feeding point is the second day of fermentation, the feeding times are respectively 2, 3, 4 and 5, and the feeding is performed every other day, wherein the feeding amount is 15g/L (the feeding is mixed sugar with glucose/xylose being 2: 1).

The concrete mode is as follows: inoculating single colony of strain L7 into YPD seed culture medium, and culturing at 25 deg.C and 140r/min for 36 hr to OD₆₀₀7.6, then inoculating 40/250mL bagasse hydrolysate medium according to the inoculation amount of 10%, fermenting at 140r/min and 22 ℃ for 9 days.

Feeding for 2 times: feeding on day 2 and day 3, respectively;

feeding for 3 times: feeding on day 2, day 3 and day 4, respectively;

feeding for 4 times: feeding on day 2, day 3, day 4 and day 5, respectively;

feeding for 5 times: feeding was performed on day 2, day 3, day 4, day 5 and day 6, respectively.

Mixed sugar (glucose/xylose 2: 1) was added at a final concentration of 15g/L per feed.

The results of the fermentations are shown in Table 3 and show that the maximum oil yield and oil content obtained with two feeding events, 20.21g/L and 57.93%, respectively, is achieved with a biomass of 34.89g/L, which is a 44%, 11% and 31% increase over batch shake flask cultures, respectively.

TABLE 3 oil production Performance of Strain L7 at different feed times

Example 6: l7 strain is fermented in 5L fermentation tank to produce oil

(1) Fermentation in batch in a fermenter

See example 4 for specific fermentation medium components and embodiments.

Producing oil by fermenting strains: inoculating single colony of strain L7 into YPD seed culture medium, culturing at 25 deg.C and 140r/min for 36h until OD600 is 7.6, inoculating into 2L bagasse hydrolysate culture medium according to 10% inoculum size, adjusting pH to 6, 22 deg.C, and fermenting for 5 days; adjusting pH with 2M NaOH during fermentation, keeping pH stable at 6, keeping rotation speed associated with DO at above 30%, and adding organosilicon defoaming agent during fermentation to control foam generated during fermentation.

The fermentation results show that: the biomass, the oil yield and the oil content are respectively 33.33g/L, 18.11g/L and 54.34 percent

(2) Fed-batch culture in fermenter

And (3) adopting a feed liquid with the ratio of glucose to xylose being 2: 1 or the ratio of glucose to xylose being 1:1 to carry out feed fermentation.

Producing oil by fermenting strains: inoculating single colony of strain L7 into YPD seed culture medium, culturing at 25 deg.C and 140r/min for 36h until OD600 is 7.6, inoculating 2L bagasse hydrolysate culture medium according to 10% inoculum size, adjusting pH to 6, and fermenting at 22 deg.C. And (3) adjusting the pH value by using 2M NaOH in the fermentation process, keeping the pH value stable at 6, correlating the rotation speed with DO, and keeping the DO above 30%. During the fermentation process, an organic silicon defoaming agent is added to control the foam generated during the fermentation process.

Feeding was performed on

days

2 and 3 with mixed sugars (glucose/xylose 2: 1, or glucose/xylose 1:1) at a final concentration of 20 g/L.

The oil content reached a maximum by day 8 of fermentation, with oil yield reaching 31.33g/L when glucose/xylose was 2: 1.

TABLE 4 oil production Performance of Strain L7 fed at different ratios

Comparative example 1

See example 4 for a difference that 80g/L total sugar was replaced by 50g/L, 60g/L, 70g/L, 90g/L, 100g/L and the biomass, oil yield and oil content after fermentation are shown in Table 5.

TABLE 5 oil production Performance of Strain L7 at different Total sugar content

Comparative example 2

See example 4 for a difference in replacing the nitrogen source soy peptone by NH₄Cl、(NH₄)₂SO₄Yeast extract, fish meal peptone, NH₄The biomass, oil yield and oil content obtained after fermentation of the Cl + yeast extract are shown in table 6.

TABLE 6 oil production Performance of Strain L7 under different Nitrogen sources

Comparative example 3

See example 4 for a difference in that 123: 1, 223: 1, 323: 1, 373: 1, 423: 1, 523: 1 were substituted for C/N273: 1 and the biomass, oil yield and oil content obtained after fermentation are shown in table 7.

TABLE 7 oil-producing Properties of Strain L7 under different C/N conditions

Comparative example 4

See example 4 for a difference in that the inoculum size was replaced by 5%, 7.5%, 12.5%, 15% 10%, and the biomass, oil yield and oil content obtained after fermentation are shown in table 8.

TABLE 8 oil production Performance of Strain L7 at different inoculum sizes

Comparative example 5

See example 4 for a difference in that 30/250mL, 50/250mL, 60/250mL and 70/250mL were substituted for 40/250mL liquid loading, and the biomass, oil yield and oil content after fermentation are shown in table 9.

TABLE 9 oil production Performance of Strain L7 at different liquid loadings

Comparative example 6

See example 4 for a difference that pH6 was replaced by pH 4, pH 5, pH 7, pH 8 and the biomass, oil yield and oil content obtained after fermentation are shown in Table 10.

TABLE 10 oil production Performance of Strain L7 at different pH

Comparative example 7

See example 4 for a difference that the temperature 22 ℃ was changed to 25 ℃, 28 ℃ and 31 ℃, and the biomass, oil yield and oil content obtained after fermentation are shown in table 11.

TABLE 11 oil production Performance of Strain L7 at different fermentation temperatures

Comparative example 8

See example 4 for a difference in that the fermentation time was changed from 8 days to 7 and 9 days, and the biomass, oil yield and oil content obtained after the fermentation are shown in Table 12.

TABLE 12 oil production Performance of Strain L7 at different fermentation times

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An oleaginous yeast, which is classified and named as Desmodium sp (Trichosporon dematis), is preserved in China center for type culture Collection in 5-21 months in 2020 with the preservation number of CCTCC NO: m2020139.

2. A method for producing an oil or fat by using xylose and glucose simultaneously, characterized in that the oil-producing yeast according to claim 1 is added to a system containing xylose and glucose.

3. The method according to claim 2, wherein the oleaginous yeast is fermented at 22-28 ℃ for 7-10 days.

4. A method for improving oil yield, which is characterized in that the oil-producing yeast of claim 1 is added into a fermentation system for fermentation and oil production; the fermentation system takes glucose and xylose as carbon sources.

5. The method of claim 4, wherein the OD is measured₆₀₀6-8 of the oil-producing yeast seed liquid is added into the fermentation liquor in an adding amount of 5-10% by volumeAnd (4) preparing the system.

6. The method according to claim 4, wherein the total sugar content in the fermentation system is 70-90 g/L; the nitrogen source is soybean peptone, NH₄Cl or yeast extract; carbon/nitrogen (273-373) to 1.

7. The method according to claim 4, wherein the fermentation liquid in the fermentation system is 12-20% and is fermented at 22-28 ℃ and pH 6-8 for 7-10 days.

8. The method according to claim 4, wherein feeding is performed during fermentation; the supplementary material is a mixture of glucose and xylose with the final concentration of 10-20 g/L, and the ratio of the glucose to the xylose in the mixture is (1-2) to 1.

9. The use of the oleaginous yeast of claim 1 in the production of oils and fats in the fields of food, medicine, agriculture, and chemical industry.